JP3564476B2 - Uninterruptible power supply control circuit - Google Patents

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a control circuit of an uninterruptible power supply device constituting an uninterruptible power supply system.
[0002]
[Prior art]
FIG. 3 is a circuit diagram showing a conventional configuration example of this type of uninterruptible power supply system.
In FIG. 3, the uninterruptible power supply system includes a commercial power supply 1 as an AC power supply, an electromagnetic contactor 2 connected to an output of the commercial power supply 1, an uninterruptible power supply 10 including a main circuit 11 and a control circuit 20, The electromagnetic contactor 15 is connected to the output of the uninterruptible power supply 10 and the load 3 of the uninterruptible power supply system. The electromagnetic contactor 2 and the electromagnetic contactor 15 are alternately excited by a sequence circuit (not shown). As a result, power is supplied to the load 3.
[0003]
The main circuit 11 includes a DC power supply 12 such as a rectified power supply and a storage battery, an inverter 13 including a semiconductor switch element, and an LC filter 14 for shaping the output voltage of the inverter 13.
Further, the control circuit 20 includes a phase difference detector 21 for detecting a phase difference between the output voltage of the uninterruptible power supply 10 and the voltage of the commercial power supply 1, and an offset setting unit 22 for correcting an offset amount of the detected phase difference. , An addition operator 23 that adds the output of the phase difference detector 21 and the set value of the offset setting device 22, and adjusts the phase of the voltage of the output of the uninterruptible power supply 10 based on the output of the addition operator 23. A frequency adjuster 24, a voltage adjuster 26 for adjusting the output voltage of the uninterruptible power supply 10 based on a command value (AC amount) of a voltage commander 25, and an output of the frequency adjuster 24 and the voltage adjuster 26 And a PWM control circuit 27 that supplies a drive signal to the inverter 13 to synchronize the amplitude, frequency, and phase of the output voltage of the uninterruptible power supply 10 with the voltage and frequency of the commercial power supply 1.
[0004]
Since each component forming the control circuit 20 of the above-described uninterruptible power supply 10 can be constructed using a known technique, detailed description of its operation is omitted.
[0005]
[Problems to be solved by the invention]
In the phase difference detector 21 for detecting the phase difference between the output voltage of the conventional uninterruptible power supply 10 and the voltage of the commercial power supply 1, the voltage ripple and waveform distortion of the output voltage of the uninterruptible power supply 10 are removed. A phase difference is detected based on the zero-cross point of the output of the filter and the zero-cross point of the voltage of the commercial power supply 1. The phase lag of the output voltage of the uninterruptible power supply 10 by the filter is determined by the offset of the offset setting unit 22. The adjustment was made according to the amount.
[0006]
However, the adjustment of the offset amount is performed by observing the waveform of the output voltage of the uninterruptible power supply 10 and the waveform of the voltage of the commercial power supply 1 using an oscilloscope or the like. Due to the voltage ripple and waveform distortion of the output voltage of the device 10, a great deal of labor and skill were required to adjust the offset amount with high accuracy.
[0007]
An object of the present invention is to provide a control circuit for an uninterruptible power supply that solves the above problems.
[0008]
[Means for Solving the Problems]
This first invention alternately closes a contact of a first electromagnetic contactor connected to an output of an AC power supply such as a commercial power supply and a contact of a second electromagnetic contactor connected to an output of an uninterruptible power supply. An uninterruptible power supply system for supplying power to a load via a contact of a closed first or second electromagnetic contactor, wherein a phase of an output voltage of the uninterruptible power supply is synchronized with a phase of a voltage of the AC power supply. In the control circuit of the power failure power supply,
A phase difference detector that detects a phase difference between the output voltage of the uninterruptible power supply and the voltage of the AC power supply, and a cross current detector that detects a cross current from the current flowing through the load and the output current of the uninterruptible power supply, A multiplying operation unit for detecting an active power component of the cross current from the cross current and a command value of the output voltage of the uninterruptible power supply, an integration operation unit for performing an integration operation of the active power component, and outputting the output; A switch inserted in the input path of the integrating arithmetic unit, an adding arithmetic unit for adding the output value of the phase difference detector and the output value of the integrating arithmetic unit, and an uninterruptible power supply based on the output of the adding arithmetic unit. A frequency adjuster for adjusting the phase of the voltage of the output of the device, and a second electromagnetic contactor performing a plurality of inching operations while supplying power to the load via the contacts of the first electromagnetic contactor. In the period during which the contact of the second electromagnetic contactor is closed by operation Time, and an operation circuit for closing the contacts of the switch.
[0009]
Further, the second invention closes at least one of the contacts of the n electromagnetic contactors connected to the respective outputs of the plurality of (n) uninterruptible power supply devices, and closes each of the closed electromagnetic contactors. An uninterruptible power supply system for supplying power to a load via a contact, wherein a control circuit of each uninterruptible power supply synchronizes a phase of an output voltage of each uninterruptible power supply with a phase of a terminal voltage of the load.
A phase difference detector that detects a phase difference between the output voltage of the uninterruptible power supply and the voltage of the load, a cross current detector that detects a cross current from the current flowing through the load and the output current of the uninterruptible power supply, A multiplying operation unit for detecting an active power component of the cross current from the cross current and a command value of an output voltage of the uninterruptible power supply, an integration operation unit for performing an integration operation of the active power component and outputting the multiplication operation unit; A switch inserted in the path from the output to the input of the integration calculator, an addition calculator for adding the output value of the phase difference detector and the output value of the integration calculator, and a switch based on the output of the addition calculator. A frequency adjuster that adjusts the phase of the voltage of the output of the uninterruptible power supply, and a plurality of inching operations performed on any one of the n electromagnetic contactors whose contacts are open, The contact of the electromagnetic contactor is closed by this inching operation. A predetermined time in periods, and an operation circuit for closing said switch.
[0010]
According to this invention, a cross current is detected from the current flowing to the load and the output current of the uninterruptible power supply, and the cross-flow active power is determined from the cross current and the command value (AC amount) of the output voltage of the uninterruptible power supply. By detecting the component, performing an integration operation on the active power component, and adding the integration operation value to the output of the phase difference detector, the phase difference can be automatically and accurately adjusted.
[0011]
Since the output of the integral computing unit can hold the adjustment amount of the phase difference, after starting up the uninterruptible power supply system, the operation of the integrating computing unit is performed several times by the operation circuit. You can do it.
[0012]
BEST MODE FOR CARRYING OUT THE INVENTION
FIG. 1 is a circuit configuration diagram of an uninterruptible power supply system according to a first embodiment of the present invention. Components having the same functions as those of the conventional example shown in FIG. Omitted.
That is, in FIG. 1, this uninterruptible power supply system includes a commercial power supply 1, an electromagnetic contactor 2, 15, a CT 4 for detecting a current flowing through a load 3, a main circuit 10 and a control circuit 31. 30 and a CT 16 for detecting an output current of the uninterruptible power supply 30.
[0013]
The control circuit 31 includes a phase difference detector 21, an addition calculator 23, a frequency adjuster 24, a voltage command value 25, a voltage adjuster 26, a PWM control circuit 27, a secondary current of CT4 and a secondary of CT16. A cross current detector 32 for detecting a cross current from the current, a multiplication calculator 33 for multiplying the detected cross current by a command value (AC amount) of the voltage commander 25 and outputting an active power component of the cross current; While the power is supplied to the load 3 via the integration calculator 34 for performing the integration calculation of the effective component, the switch 35, and the contact of the electromagnetic contactor 2, the electromagnetic contactor 15 is caused to perform the jogging operation a plurality of times. An operation circuit for closing the contact of the switch for a predetermined time within a period in which the contact of the electromagnetic contactor is closed by a dynamic operation.
[0014]
The operation for adjusting the phase difference offset detected by the phase difference detector 21 of the uninterruptible power supply 30 will be described below.
As shown in FIG. 1, the operation circuit 36 causes the electromagnetic contactor 15 to perform a plurality of inching operations while the power is supplied to the load 3 in a no-load state from the commercial power supply 1 via the closed electromagnetic contactor 2. If there is a phase difference between the voltage of the commercial power supply 1 and the output voltage of the uninterruptible power supply 30 during a period (for example, about 50 to 60 milliseconds) during which the contact of the electromagnetic contactor 15 is closed due to the inching operation. , A cross current is detected in the output of the cross current detector 32, and a multiplication operation value of the cross current and a command value (AC force) of the voltage command device 25 equivalent to the voltage of the commercial power supply 1, that is, the terminal voltage of the load 3, is Outputting this cross-flow active power component is a known technique.
[0015]
When the contact of the switch 35 is closed for a predetermined time (for example, about 5 milliseconds) within the period in which the contact of the electromagnetic contactor 15 is closed, the integration calculator 34 performs integration of the active power component. After that, when the contact of the switch 35 is opened, the output value of the integration calculator 34 retains the immediately preceding value, and the inching operation is performed two or three times, whereby the phase difference offset amount detected by the phase difference detector 21 is detected. Is adjusted.
[0016]
The reason why the period during which the integration operation of the integration operation unit 34 is performed is set to about 5 milliseconds is that after the offset amount of the phase difference is adjusted via the addition operation unit 23, the output of the phase difference detector 21 is adjusted. This is because the frequency adjuster 24 adjusts the phase of the voltage of the output of the uninterruptible power supply 30 based on
FIG. 2 is a circuit configuration diagram of an uninterruptible power supply system showing a second embodiment of the present invention. Components having the same functions as those of the first embodiment of the present invention shown in FIG. The description is omitted.
[0017]
That is, the difference from FIG. 1 is that this uninterruptible power supply system has an uninterruptible power supply 30 and uninterruptible power supplies 40 and 50 having the same configuration as the uninterruptible power supply 30, that is, a total of three units. Power is supplied to the load 3 via the power supply 41, 51, and the output current of each uninterruptible power supply 40, 50 and the secondary current of the CT 4 are used to determine the phase of the output voltage of the power supply 40, 50 and the terminal of the load 3. After the operation of adjusting the offset amount of the phase difference from the voltage phase is performed as described above, the uninterruptible power supply devices 30, 40, and 50 perform parallel operation.
[0018]
【The invention's effect】
According to the present invention, a cross current is detected from the current flowing to the load of the uninterruptible power supply system and the output current of the uninterruptible power supply, and the cross current is detected from the command value (AC amount) of the output voltage of the uninterruptible power supply. By detecting the cross-flow active power component, performing an integral operation of the active power component, and adding the integral operation value to the output of the phase difference detector, the phase difference is automatically and accurately adjusted. be able to.
[0019]
In particular, the adjustment can be made without using any special measuring device even at the place where the uninterruptible power supply system is installed.
[Brief description of the drawings]
FIG. 1 is a circuit configuration diagram of an uninterruptible power supply system showing a first embodiment of the present invention; FIG. 2 is a circuit configuration diagram of an uninterruptible power supply system showing a second embodiment of the present invention; FIG. Circuit diagram of uninterruptible power supply system showing
DESCRIPTION OF SYMBOLS 1 ... Commercial power supply, 2 ... Magnetic contactor, 3 ... Load, 4 ... CT, 10, 30, 40, 50 ... Uninterruptible power supply, 11 ... Main circuit, 12 ... DC power supply, 13 ... Inverter, 14 ... LC filter , 15, 41, 51: electromagnetic contactor, 16: CT, 20, 31: control circuit, 21: phase difference detector, 22: offset setter, 23: addition operator, 24: frequency adjuster, 25: voltage Commander, 26: voltage regulator, 27: PWM control circuit, 32: cross current detector, 33: multiplication operator, 34: integration operator, 35: switch, 36: operation circuit.

Claims (2)

The contact of the first electromagnetic contactor connected to the output of an AC power supply such as a commercial power supply and the contact of the second electromagnetic contactor connected to the output of the uninterruptible power supply are alternately closed, and the closed first or An uninterruptible power supply system for supplying power to a load via a contact of a second electromagnetic contactor,
In the control circuit of the uninterruptible power supply that synchronizes the phase of the output voltage of the uninterruptible power supply with the phase of the voltage of the AC power supply,
A phase difference detector that detects a phase difference between the output voltage of the uninterruptible power supply and the voltage of the AC power supply,
A cross current detector that detects a cross current from the current flowing through the load and the output current of the uninterruptible power supply,
A multiplying operation unit for detecting a cross-flow active power component from the cross-flow and a command value of an output voltage of the uninterruptible power supply;
An integration calculator that performs integration calculation of the active power component and outputs the integration calculation;
A switch inserted from the output of the multiplication operator to the input path of the integration operator,
An addition calculator for adding the output value of the phase difference detector and the output value of the integration calculator,
A frequency adjuster that adjusts a phase of a voltage of an output of the uninterruptible power supply based on an output of the addition arithmetic unit;
While the power is being supplied to the load via the contact of the first electromagnetic contactor, the second electromagnetic contactor performs a plurality of inching operations, and the period in which the contact of the second electromagnetic contactor is closed by the inching operation A control circuit for closing a contact of the switch for a predetermined time within the control circuit. At least one of the contacts of the n electromagnetic contactors connected to the output of each of the plurality (n) of uninterruptible power supplies is closed, and power is supplied to the load via the contacts of the closed electromagnetic contactors. An uninterruptible power supply system
In the control circuit of each uninterruptible power supply that synchronizes the phase of the output voltage of each uninterruptible power supply with the phase of the terminal voltage of the load,
A phase difference detector that detects a phase difference between an output voltage of the uninterruptible power supply and a voltage of the load;
A cross current detector for detecting a cross current from the current flowing through the load and the output current of the uninterruptible power supply,
A multiplying operation unit for detecting an active power component of the cross current from the cross current and a command value of the output voltage of the uninterruptible power supply;
An integration calculator that performs integration calculation of the active power component and outputs the integration calculation;
A switch inserted in the path from the output of the multiplication operator to the input of the integration operator,
An addition calculator for adding the output value of the phase difference detector and the output value of the integration calculator,
A frequency adjuster that adjusts a phase of a voltage of an output of the uninterruptible power supply based on an output of the addition arithmetic unit;
Out of the n electromagnetic contactors, one of the electromagnetic contactors whose contacts are open is caused to perform a plurality of inching operations, and the inching operation closes the contacts of the electromagnetic contactor. And a control circuit for closing the switch for a predetermined time within a given period.

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